Rapport des sexes, effort et succès de reproduction chez Rubus chamaemorus , plante herbacée vivace dioïque de distribution subarctique

• Published in: Canadian Journal of Botany
• Main Authors: Dumas, Pascale, Maillette, Lucie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1987
• Subjects: Plant Science; Rubus chamaemorus; Subarctic; subarctique*
• Online Access: http://dx.doi.org/10.1139/b87-354; http://www.nrcresearchpress.com/doi/pdf/10.1139/b87-354

Studies published on the reproductive success of dioecious species concentrate on the role of sex ratios and pollinator behaviour. In the case of Rubus chamaemorus L., a circumboreal dioecious species, we hypothesized that flower survival and biomass allocation to reproductive tissues, which are climate dependent, also influence fruit production. Only 0.05% of total biomass is allocated to reproduction, whereas 94% goes to underground organs responsible for vegetative propagation. Many male (28 – 51%) and female flower buds (35 – 54%) and young fruits (24–51%) die prematurely mainly because of the climate; fruit production then becomes independent from initial female flower density. The scarcity of female flowers at most sites (except near open water) limits fruit production. The limited sexual reproduction would allow cloudberry to maintain somatic resources, thereby increasing the longevity of individuals and their chance of encountering the climatic conditions required for reproductive success. Such a strategy is adaptive in a variable climate like that of the subarctic. Furthermore, the reduced importance of sexual reproduction would diminish the need to optimize sex ratios. Other selective pressures (e.g., competition) would then favour male clones in most sites, in spite of the unproductive pollen excess.